Rifle bullets and some handgun ones can shoot through brick (and most other) walls and the length of cars easily, nevermind the shields of old. I can see it as being somewhat practical if the shields had kevlar in them or something but even then a bunch of bullets or an automatic rifle would tear it apart. it'd only really be useful against low powered handgun fire, but I guess you can still implement it if you don't really care about realism.
Against 200 year old guns and ammunition. And yes I won't expect it to stop a .50cal bullet... Also, it can be used as soft cover. He may shoot throught, but he can't directly aim at important things. The legion is not exactly realistical.... keep in mind they manage a draw against guys with heavy machineguns and marksmans.... with just a bunch of lawnmower blades....Granted, it's more "Rule of cool" then realism....
A modern testudo formation:
[img]http://img137.imageshack.us/i/zdjecie1060125585fbebecb1.jpg[/img]
And if we go up against magnum ammunition:
http://en.wikipedia.org/wiki/Ballistic_shield Ballistic shields.
Keep in mind the US had a pretty big riot at its hands mere months before the bombs fell... its quite possible that all those riot response groups had such shields and the legion got them all
Different types:
Wooden shield:
most roman design, with scrapmetal and kevlararmors nailed on
Tactical Riot shield:
standart police equip, painted red, slightly reinforced
Tactical electrified Riot shield:
Yes those things exist really. Touch it from the wrong end and you won't touch it agian.
Ballistic Shield:
For Cesars bodyguards and high ranking guys. Weights quite something and slows down. But stops anything except of a .50cal rifle